One of technologies for performing communication on a network is “data encapsulation”. The details are as follows.
A data transferred between networks constitutes its form in accordance with a communication system used at the time of the transfer. The communication on the network is performed through a plurality of layers, as represented by OSI Reference Model and TCP/IP stack. Therefore, the form of the data needs to be capable of supporting specification of each layer. In general, a data consists of a header and a payload. The header includes a content that serves as a control data at a specific layer, and a communication standard at that layer interprets the content of the header to forward the payload to another layer. At each layer, the header is added ahead of the payload at a time of transmission and the header is removed at a time of reception. Therefore, the payload includes a content that can serve as the header at an upper layer. When a data communication is initiated, a data is generated from the top layer of the communication system. The data passes through lower layers one after another, passes through the bottom layer and then is output to the network. Before the data reaches the bottom layer, the header associated with each layer is added to the data and a portion being the header at the upper layer is treated as the payload. The addition of the header thus performed is called the data encapsulation.
The data encapsulation can be regarded as a technique that makes it possible by adding the header associated with a specific communication system to communicate with the communication system with which communication has not been available. By the application of this technique, it is possible to improve data security and to create a new communication system that can support a plurality of existing communication systems.
A new communication system that utilizes this technique is described in Non-Patent Literature 1. According to Non-Patent Literature 1, “Fibre Channel Over Ethernet (FCoE)” is proposed as one technique for a recent data center.
A recent data center is operated with a network configuration in which Storage Area Network (SAN) as represented by Fibre Channel (FC) and Local Area Network (LAN) as represented by Ethernet (registered trade mark) are mixed. Since separate networks are mixed, management costs and device costs are rising, which is a problem.
Because of this situation, the FCoE has been proposed. According to the FCoE, an FC data is encapsulated by using an Ethernet header and a newly-defined FCoE header. As a result, it is possible to integrate the communication system into the Ethernet system and to achieve a network configuration that the SAN and the LAN are integrated. Since uniform management and devices can be achieved on the integrated network, the FCoE is considered as a promising technique for solving the problem.
However, according to the current FCoE, the communication needs to invariably go through an FCoE communication-dedicated switch that is called an “FCoE Forwarder (FCF)”. This causes constraint on network flexibility and extensibility. Therefore, it is not possible to deal with the data center configuration that utilizes a large number of nodes.